Can and can end unit



April 9, 1968 v. c. KUTKA CAN AND CAN END UNIT Filed Jan. 3O, 1967 A mm u WK, F a MM E J m7 h 2W W 6 4 .m I

United States Patent Oil" 3,376,997 CAN AND CAN END UNIT Vincent C. Kutka, Chicago, Ill, assignor to National Can Corporation, Chicago, 11]., a corporation of Delaware Filed Jan. 30, 1967, Ser. No. 612,567 7 Claims. (Cl. 220-48) ABSTRACT OF THE DISCLOSURE A can cover having a serrated curl portion, and a can in which the end hook radius portion of the double seam fastening the end to the container body has a coined or serrated surface. This construction is particularly useful Where the can body is made from fibre or other soft material.

Background of the invention (1) Field of the invention.The present invention relates generally to can manufacture and particularly to the manufacture of can ends for metal .or fibre cans and to the construction of a can resulting from seaming an end onto a can body and imparting a coined, serrated, notched or toothed edge to the end hook radius of the double seam for engaging a can opener. The provision of a can with a coined double seam in the end hook radius portion thereof renders the can easy to open when a conventional opening tool is used on the can. Because difficulty has been experienced using many ordinary can openers on cans with fibre bodies, the invention is particularly useful when incorporated into fibre-bodied cans, although the exact construction of the can end and the can end seam is novel and useful with any container opened by an ordinary can opener in which a gear engages the double seam of a can to cause a cutting blade to circle the double seam and cut the can end.

(2) Description the prior art-It is now known that it is difficult satisfactorily to open a fibre bodied or so-called composite can with the aid of a normal, inexpensive can opener of the type in which a geared or toothed drive wheel engages the lower outside edge of a can end scam in the area known as the end hook radius of the seam and propels a cutting blade around the inside or chuck wall radius or chuck panel portion of the can end to cut the cover so it may be removed from the can. The present invention relates to an improvement in can ends and in double seams by which the end is fastened to the container.

Cans of the type on which the present invention is an improvement are referred to and are well known in the prior art as composite cans. By composite can is meant a can having a fibre or plastic body and a metal end. Such fibre can bodies and the method of their manufacture are well known in the can making art. These cans and methods of making them are illustrated, for example, in Dunlap et al., Patent No. 3,159,515, issued December 1, 1965, Rutledge, Patent No. 3,183,802, issued May 18, 1965, Krause, Patent No. 3,156,401, issued November 10, 1964, and Miller, Patent No. 3,147,902, issued September 8, 1964. These patents illustrate a so-called spiral wound can in which one long, continuous body is formed by spirally overlapping a plurality of plies from separate spools, after which the lengthy body thus formed is cut into shorter discrete can bodies.

Another type composite container is a so-called lap seam container, in which a plurality of fibre layers are laminated to each other, to form a single, multiple-ply sheet, after which the sheet thus formed is formed into a cylindrical shape with an overlapping seam, which is 3,376,997 Patented Apr. 9, 1968 then held in place by glue or the like. This is a so-called lap seam can body.

A third major type of can, commonly used for frozen juices and the like, is made by simply winding one ply .of material around a mandrel a number of times to form a cylinder, then cutting the material transversely of its length and longitudinally of the length of the container, gluing the hook end thus formed onto the body and coating the inside of the resultant can body, thereafter aflixing one or more ends to such body. This is known as a convolute can.

In addition, plastic cans are made by seaming a metal end to a one-piece blown or extruded plastic body.

Normally, any of the above style containers is opened by the use of an inexpensive can opener in which a cutting blade is propelled around the double seam of the container by means of the teeth on the can opener drive wheel.

However, the great majority of composite cans heretofore manufactured have not been opened by an ordinary can opener, since most of these cans have been used for motor oil, in which case a filling station operator punctures the can with a specialized tool and does not remove the end therefrom, or such cans have been used to pack frozen juices, foods, and other high profit specialty items in which the cost of an expensive, so-called easy opening device can be justified.

However, as composite cans have become more popular for other uses, such as for containing solid shortening and other products which do not require containers able to withstand substantial pressure or vacuum, a dissatisfaction has been noted in the manner in which an ordinary can opener operates to open such cans. Many products are now packed in these cans for reasons of economy, and many such cans are directed to the institutional trade. In such cases, the extra cost of an easy opening feature cannot be justified, but the extra effort required to open such a can is a definite drawback to the sale .of the package.

Since the majority of cans marketed today are still being made of metal, most inexpensive can openers are made with a particular space between the drive wheel and the blade so that the opener rides around the seam at a given angle and distance relative to the seam while the blade cuts the can end. In the case of a metal can, even if the angle and wheel-blade distance are not precisely those desired, the opener cannot cut into the body, and generally obtains a grip or bite on the double seam which is good enough to open the can satisfactorily.

In a fibre can, however, the can body is much thicker than a metal body. Therefore, because of the thickness of the fibre body, the gear wheel of the can opener tends to become disposed, in use, in an improper position, and tends to cut into the fibre can body. Since a fibre can does not have the toughness of metal so as to withstand penetration by the gear wheel, the wheel soon becomes imbedded in the fibre and the opener cannot be advanced around the seam. In addition, the fibre from the can body becomes wedged between the drive gear and the double seam, and the toothed driving wheel, with the fibre interposed between it and the seam, merely slips and does not advance the cutting blade.

Summary of the invention Accordingly, an object of the present invention is to provide a can end having a serrated or coined surface on the end hook radius portion of the double seam of the end to render the can easier to open.

Another object is to provide a can end having a coined edge which can be placed on the can end before the end is seamed onto a can body.

Another object is to provide a can seam construction which provides improved means of adhesion between a can opener wheel and such double seam.

The present invention achieves its objects and provides a simple and economical solution to such a problem, by providing teeth or serrations in the end hook radius of the can end, thereby giving the edge of the seam a coined texture. It has been found that, even where a portion of the opener drive wheel bites into the body of the can, the serrations on the end are sufficient to enable the remainder of the drive wheel of the opener to engage or grip the can end satisfactorily.

The invention is also advantageously used with metal cans, inasmuch as the driving wheels or gears of many inexpensive openers are of a soft, stamped steel construction which renders it difiicult for them to penetrate the tough metals now being commonly used on can ends. Thus, it is well known in the can making art that metals are much tougher today, since corresponding can parts of the same strength are now made with metals having only about half the thickness of corresponding units made only 10 or 15 years ago.

These and other objects and advantages of the present invention, including those inherent therein, and the manner of their attainment, will become more apparent when considered in conjunction with a description of the preferred embodiment of the invention contained in the following specification and claims, and as shown in the drawings below, in which like reference numerals denote corresponding parts throughout.

Brief description the drawings FIG. 1 is a side elevational view, with parts broken away, showing a can embodying the present invention;

FIG. 2 is a vertical sectional view through a portion of a conventional can end double seam, showing a can opener cutting a metal end from a can with a metal body;

FIG. 3 is a greatly enlarged vertical sectional view, similar to FIG. 2 but showing an opener attempting to cut through a metal end attached to a fibre body;

FIG. 4 is a schematic view of a section of a can end, illustrating the nomenclature applicable thereto;

FIG. 5 is a side elevational view of a can end seam according to the present invention; and

FIG. 6 is a vertical sectional view of a portion of the can end of FIGS. 1 and 3.

Description of the preferred embodiments Referring now to FIG. 1, it will be noted that there is shown generally a can 10 having a cover element 12 surrounding and fastened to a body wall 14 by means of a double seam 16.

FIG. 2 shows a can opener unit 18 cutting radially outside portion 20 of the cover element 12, just inside the seam 16.

FIG. 2 illustrates a normal method of opening a can constructed of ordinary materials and ordinary dimensions. In this situation, a can opener 18, generally comprising a driving wheel 22 operated by a handle 24 propels a cutting blade 26 around the outer edge portion 20 of a cover 12. The cutter 26 is pivotally mounted, as by a rivet 28 to a frame 30 which also includes an upper edge guide 32 and a lower edge guide 34. The lower edge guide 34 engages the side wall 14 of the can while the upper edge guide 32 rests on the top of a double seam 16. Contact between the wheel 22 and the seam 16 is in the area of the end hook radius 36 of the can 10. In conventional can openers of the sort illustrated, a given distance separates the bottom of the cutting blade 26 from the inside surface 38 of the drive wheel 22. Likewise, there is a given distance separating the intermediate portion 40 of the frame 30 and the blade 26. The significance of these distances will be discussed more fully herein.

It will be seen that, Whereas FIG. 2 shows an opener opening a metal can body, FIG. 3 shows an opener with a wheel 22 and blade 26 opening a can having a fibre wall body 42. FIG. 3 shows that the wheel 22 is not squarely contacting the end hook radius portion 36 0f the double seam 16, but illustrates that a displaced portion 44 of the fibre body wall 42 has become wedged between the wheel 22 and the end hook radius 36. Also, it will be seen that the wheel 22 has cut inwardly into the fibre body 42 for reasons which will be discussed in detail further herein.

FIG. 3 also illustrates nomenclature which is commonly applied, in the can industry, to components of a double seam 16, which fastens an end 12 onto a can body. Thus, FIG. 3 shows an end hook 46, an end hook radius 36, a seaming wall 48, a seaming wall radius 50, a seaming panel 52, a seaming panel radius 54, a chuck wall 56 and a chuck wall radius 57. The double seam 16 also includes a body wall 42, a body hook 58, and a body hook radius 60.

Thus, it will be seen that going from the outside portions of the can end or can body to the inside portions, each principal part is joined to the next succeeding part by a curve or radius which derives its name from the part located just outwardly thereof.

FIG. 4 illustrates the terminology applied to a can end 12 before it has been attached to a container. This illustration shows a curl 62, seaming panel 64, a seaming panel radius 66, a chuck wall 68 and a chuck wall radius 70.

FIG. 6 shows three measurable dimensions in a typical can, namely the thickness of the body wall A, the width of the double seam B, and the height of the double seam C.

In keeping with the present invention, a plurality of setrations or indentations 72 are formed in the end hook radius area 36 of the seam 16. Thus, it can be seen in FIGS. 5 and 6, that the indentations or serrations 72 may be made by imparting notches or indentations 72 which extend upwardly somewhat above the bottom surface 74 of the end hook radius 36.

In accordance with the present invention, these serrations 72 are formed in the curl 62 of a can end, whereupon the end 14 is joined by seam means 16 to a fibre body 42. Thereafter, this can is opened with an ordinary can opener. Although the body wall 42 may be noticeably cut or scored by the inside edge 38 of the wheel 22, the can is easily and conveniently opened with an ordinary can opener.

When a can which is otherwise identical but does not have the serrations 72 in the end hook radius of the double seam, a condition such as that shown in FIG. 3 comes about, and since the displaced body wall portion 44 is wedged between the end hook radius 36 and the wheel 22, it is difiicult to open the can end, since the wheel 22 slips and delivers erratic and unsatisfactory performance.

Although the reasons for the easier opening brought about by this improvement are not understood with absolute certainty, it is believed to be accounted for by the following. In an opener of the type illustrated there are given distances between the inside edge 38 of the wheel 22 and the blade 26 and between the intermediate portion 40 of the frame 30 and the blade 26. In the case of an all metal can, there are approximately five thicknesses of metal which account for the width of the double seam (dimension B, FIG. 6). This dimension is normally about .035 inch to .040 inch assuming the seaming is quite tight and the thickness of the end metal is approximately .008 inch (3 thicknesses) and the body metal is approximately .006 inch (2 thicknesses).

Thus, the blade 26 might be spaced from the inside edge 38 of the wheel 22 a distance equal to two to five times the thickness of the body wall 14, that is, about .010 inch to .040 inch. Thus, allowances made for the thickness of the body wall 14 as well as for the fact that the blade 26 will not cut the end immediately adjacent the body wall, but cuts the end inwardly a distance equal thereto plus the thickness of the chuck wall 56, and makes allowance for the fact that the blade does not cut exactly at the bottom of the chuck Wall 56, but through the chuck wall radius portion 57 of the end. In addition, it is well known that the chuck wall 56 is not truly vertical, but may be inclined upwardly and outwardly, that is upwardly and to the left as in FIG. 3.

On the other hand, when such an opener is used with a fibre can, the thickness of the wall may range from a thickness of .026 inch, or less, in the case of a small frozen juice can, to a thickness of .056 inch, or more, in the case of a large container for shortening, motor oil, etc. If the distance between the blade 26 and the inside edge 38 of the wheel 22 remains relatively constant, the inside edge 38 of the wheel 22 will tend to move inwardly to the position shown in FIG. 3, reference being had to the fact that in the larger, thicker cans, the end metal 12 is thicker and the stiffness in bending of the chuck wall radius is significant.

In addition, since the angle of the intermediate portion 40 of the opener frame from the vertical is determined at least partially by the length of the edge guide 34 in relation to the width B of the double seam 16, a thicker seam 16 tends to make the frame portion 40 more upright. This aggravates the problem, because it forces the edge 38 of the wheel 22 into the body wall 42 instead of allowing the opener to tilt inwardly and effectively alter the blade-wheel distance.

However, when cans are made with the improvement described herein, the wheel 22 is able to engage the notches 72 on the bottom of the seam 16 and gain a required additional grip necessary to cut the ends satisfactorily even if a displaced portion 44 of the body wall 42 is wedged between the wall 22 and the seam end hook radius 36.

In the preferred embodiments of the invention, the notches or serrations vary in depth between .003 inch and .020 inch, and are preferably spaced apart from about .020 inch to .090 inch. It will be noted that these notches may be in the metal itself, as in the form of a cut, or may be at least partly small dents or indentations in the seam 16, as illustrated for example in FIGS. and 6. The notches may also be a combination cut and indentation or re-entrant.

Forming the coined surfaces or notches may be done by conventional means. For example, if it is desired to impart serrations 72 to the can end before it is seamed onto the container, the ends may be placed, in batches if desired, into a lathe or like rotary tool and can be notched by engaging a knurling tool with the curl portion 62 thereof in a known manner. Likewise, the serrations 72 may be imparted by placing a toothed die in the conventional end curler. These curlers, exemplified by a Bliss brand end curler, are well known in the can art and comprise a drive wheel which rotates while in contact with the inner end of a can end and rolls the outer edge of a can end against a curling die.

On the other hand, conventional ends may be put on the body and the serrations 72 may be imparted to the end when the end is double seamed onto the can. A conventional Angelus brand or other well known double seamer may be used for this purpose by imparting a toothed surface to the so-called second operation seaming roll, which is well known in the can making and filling art.

It can thus be seen, from the above description, and from the appended claims, taken in conjunction with the drawings, that the present invention provides a new and useful can and can end unit having a number of novel advantages and characteristics, including those hereinbefore pointed out and others which are inherent therein. I contemplate that certain changes and variations may be made by those skilled in the art without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In a can unit adapted to be opened by a can opener circling the seam thereof, said can unit including a side wall portion, a metal can end unit, and at least one seam means connecting said side wall portion to said can end unit, and in which one element of said seam means comprises a body book, a body hook radius, and a body wall, and in which another element of said seam comprises an end hook, an end hook radius, a seaming wall, a seaming panel, and a chuck wall, the improvement comprising: a plurality of closely spaced serrations located in the end hook radius of said seam, said serrations being constructed and arranged to engage the drive wheel of a can opener, whereby opening of said can end is facilitated.

2. A can unit as defined in claim 1 in which said side wall portion of said can unit comprises a fibre material.

3. A can unit as defined in claim 1 in which said side wall portion of said can unit comprises a fibre material having a thickness of about .020 inch to about .060 inch.

4. A can unit as defined in claim 1 in which said side wall portion of said unit comprises a plastic material.

5. A can unit as defined in claim 1 in which said serrations have a depth of from about .003 inch to about .020 inch.

6. A can unit as defined in claim 1 in which said serrations are spaced apart a distance of about .020 inch to about .090 inch.

7. In a metal can end adapted to be seamed onto a container body to form a container, said can end comprising an end panel, a chuck wall, a seaming panel, and a curl portion, wherein, upon being seamed to said container body, said curl portion will form, at least in part, an end hook radius portion, the improvement comprising: a plurality of serrations located in said curl portion and closely spaced from each other, said serrations being adapted to engage the drive wheel of a can opener when said curl is formed into an end hook and an end hook radius and said end is seamed onto said container body.

References Cited UNITED STATES PATENTS 1,609,604 12/1926 Blake 22048 THERON E. CONDON, Primary Examiner. J. B. MARBERT, Assistant Examiner. 

